Abstract The results of the structural study of chain-like structured TlInSe2 compound using powder synchrotron X-ray diffraction (XRD) experiments under the pressures up to P = 30.53 GPa and a first principle analysis of structural and elastic properties under the pressures up to P = 50 GPa are reported. The XRD data show the stability of the tetragonal phase in the whole investigated pressure range. Density Functional Theory (DFT) calculations also evidence that at zero pressure the lowest energy structure of TlInSe2 is tetragonal (space symmetry group I4/mcm). At pressures above P ≥ 38 GPa the symmetry of the lowest energy structure changes to face-centered cubic one (Fm-3m). It was shown that the experimentally and theoretically obtained pressure dependences of lattice parameters in tetragonal phase are in good agreement. The pressure dependences of elastic constants, acoustic wave velocities and other elastic parameters, such as bulk modulus, shear modulus, Young's modulus, Poisson's ratio have been calculated.

中文翻译：

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高压下 TlInSe2 的结构和弹性特性

摘要 使用粉末同步加速器 X 射线衍射 (XRD) 实验在高达 P = 30.53 GPa 的压力下对链状结构的 TlInSe2 化合物进行结构研究，并对高达 P 的压力下的结构和弹性性能进行第一性原理分析。 = 50 GPa 报告。XRD 数据显示了四方相在整个研究压力范围内的稳定性。密度泛函理论 (DFT) 计算还证明，在零压力下，TlInSe2 的最低能量结构是四方的（空间对称群 I4/mcm）。在压力高于 P ≥ 38 GPa 时，最低能量结构的对称性变为面心立方 (Fm-3m)。结果表明，实验和理论上获得的四方晶格参数的压力依赖性非常吻合。